Although nitrites play a crucial part in aquarium life, if the levels of nitrites are too high, there can be serious problems.
If you want to find out what nitrites are, what problems they can cause for your fish and how to combat these issues, keep reading.
In this post, we are going to dive into the dangers of nitrites and learn the different ways to lower them in your fish tank.
Before moving on, we should point out that we are specifically talking about nitrites, not nitrates.
They are very different from one another.
What Are Nitrites?
Nitrites are, in simple terms, dissolved nitrogen that occur naturally within the water column (inside your tank).
This product begins with waste, and in your aquarium waste can be from dirty filters, fish excrement, decaying plants and uneaten fish food.
Waste is not the defining cause of high nitrite levels in your aquarium, though.
Where Do Nitrites Come From In An Aquarium?
As mentioned above, nitrites are in the water because of waste.
However, the cycle is not that straightforward.
There are three steps in the process of nitrites being created, and it begins with waste:
The waste (from feces, food, filters or rotting plants) breaks down and gives off ammonia
The ammonia is broken down by bacteria named nitrosomonas, producing nitrites
The nitrites are then fed on by bacteria called nitrobacter, which then produces nitrates.
In simple terms, nitrites (and nitrates) would not exist if there was no ammonia in the environment.
Aquarium Nitrite Levels
Although different fish species can survive in various nitrite levels in their tank, the percentage it should be at is zero.
Even if a fish can survive with nitrite levels in the water, it is not a good thing and can be very strenuous for them.
So, you should have a reading of 0 ppm (parts per million).
Any level higher than 0 ppm in a tank is considered bad, unless you are in the process of establishing a new tank.
In new tanks, there is not enough bacteria to break down the nitrites when they are produced, so higher levels are expected.
If you are not cycling a new tank, however, you will need to find the cause of your problem as soon as you can and get it resolved before any serious damage in done.
High Nitrite Levels
If the nitrite levels in your aquarium water is too high, your fish will suffocate.
As strange as that sounds, it is true.
The nitrites will be absorbed by the fish and restrict the amount of oxygen in the creature’s bloodstream.
The higher the nitrite levels are, the less oxygen your fish can use and the faster they will suffocate and die.
No matter how many aquarium bubblers or surface agitation you have, which oxygenate the water, your fish will die.
This is because the fish will not be able to actually draw oxygen from the water.
This horrible process is called nitrite poisoning.
What Causes Nitrites in Aquariums?
There are five main reasons for high nitrite levels in aquariums.
We will go through each of them in the sections below.
If There Are No Nitrifying Bacteria In The Filter Of Your Tank
If you do not have the correct bacteria that create essential nitrite from ammonia nitrite, you will likely experience nitrite poisoning very quickly.
Feeding Your Fish Too Much
Because fish eat, they will also excrete waste.
It is this waste that will cause high levels of ammonia and therefore nitrites.
Additionally, giving your fish too much feed will also result in high ammonia and therefore nitrite levels.
You should only feed your fish as much as they can eat in two minutes or less, or else it will simply rot on the bottom of the tank.
Buildup Of Waste
This waste can include the fish excrement, dead fish or dead plants.
The moment anything starts to decay in the aquarium, the water will get polluted.
As the waste matter decays, ammonia will be released into the tank.
Too Many Fish In The Tank
Having too many fish in one tank can be bad for several reasons, and this is one of them (along with potentially bringing on bacterial and algae bloom).
Too many fish in one tank will cause the waste to be more concentrated.
If you cannot filter out this waste somehow, your fish will soon pay the price.
If your filters do not work properly, all the pollutants and waste will be left in the tank.
When this happens, waste will accumulate and the ammonia will result in nitrites.
This is one of the leading causes for nitrite poisoning for fish, and so should be one to look out for.
A few other reasons for high nitrite levels in your tank could include:
- You have a new aquarium (it is less than two months old)
- You recently cleaned the substrate and filters (or changed them)
- You have not recently pruned the live plants in your fish tank (causing decay)
- You feed your fish twice a day or more
- You have a fish tank that is 10 gallons or smaller
- You added ice to the tank to cool it down
- You added too many fish to the tank at the same time
- You used an antibiotic without taking the biological filter out first
- You did not / were not able to remove the body of a dead fish quickly
- You carried out a water change and did not de-chlorinate beforehand
Testing For Nitrites
You can buy nitrite testers from stores or online.
There are many to choose from, and they will all do the same job, so the choice is up to you.
Signs And Symptoms Of Nitrite Poisoning
There are a few signs to look out for when it comes to nitrite poisoning.
If you spot any of these symptoms in your fish, take immediate action and get your water tested.
Common symptoms include:
- Lethargic fish when they are usually active
- The gills of the fish are dark
- The fish are gasping for breath and their gills are moving quickly
- Fish try to stay near the surface of the water
- One or more fish seem unhealthy or even dead
What To Do To Protect Your Fish If Nitrite Levels Are High?
If you have discovered that the water in your aquarium has high levels of nitrites, you can:
Add An Air Stone
Adding an air stone to your aquarium will add more oxygen to the water.
This should help the fish breathe a little easier, but it is not a long-term solution.
Relocate All Your Fish To A Tank That Is Already Established
If you have a spare aquarium that has already been established, relocate your fish over to it so that you can deal with the nitrites safely.
This is not always an option, however, as many people do not have more than one functioning tank they can use.
Add Rock Salt To The Aquarium
You need to be careful with this one.
Some species of fish do not have scales (such as loaches and corydoras) and are therefore super sensitive to salt.
Do some research to check if your fish can handle some salt, and if they can, you should add one teaspoon of non-iodized salt per 10 gallons of water.
Doing this will enhance the levels of chloride that are already present in the water.
These elevated levels of chloride will prevent the nitrites from entering through the gills of your fish.
Reducing Nitrite Levels In Your Aquarium
If you find out that your nitrite levels are high, there are a few things you can to do to try and bring them down, so don’t worry too much yet.
Change Your Water
The first thing you should do is do a water change.
In this case, you should do a 30-50% water change to help get rid of the nitrite spike.
By doing this, you are adding nitrite-free water and diluting the nitrites that are already in the aquarium.
This method will buy you some time so that you can properly deal with the nitrite levels (points below).
Use Water Conditioner
Water conditioner is a nitrite remover in a handy bottle.
All you need to do is go out and buy one and use it per the instructions on the back.
These handy conditioners bind the nitrates, which makes them harmless to the fish in the tank.
This gives the bacteria in your filter the chance to do their job and turn the nitrites into nitrates.
Try Using Recycled Filters
For this reason, it is always handy to have some older filters around.
Since these filters already have beneficial bacteria on them, swapping out some newer filters for these will give the aquarium a boost.
The bacteria on the old filters will get to work and turn the nitrites into nitrates quickly.
Preventing High Nitrite Levels In Your Aquarium
In order to prevent nitrite spikes in your aquarium, you will have to maintain and nitrogen cycle that is stable.
An important part of this is ensuring that you have beneficial bacteria that is healthy and well cared for.
To maintain a healthy cycle, you need to carry out the following steps.
As we previously covered, having too many fish in a single tank will increase the waste, which will then increase ammonia and nitrite levels.
Get A Bottom Feeder Creature
Bottom feeder are great ways to keep the tank clean and free of all kinds of things.
Some bottom-feeders include rubber lipped plecos, which are an excellent choice if you are on a budget.
Clean Your Filters Regularly
You should regularly clean your filters, but not all at the same time.
The beneficial bacteria also live on the filters, so if you clean them all at the same time, you are getting rid of them all.
Do Not Feed Your Fish Too Much
Feeding your fish once a day is a great place to start when maintaining a balanced nitrite cycle.
Any food that is left over from feeding will eventually start to decay and produce ammonia, which causes nitrites.
Ideally, you should feed your fish as much as they can finish in two minutes or less.
Get A Gravel Vacuum
If you cannot get a bottom feeder, get a machine to do it for you.
Gravel vacuums will get rid of all the decaying food and other unwanted waste that sits on the tank substrate.
Using this machine every time you do water changes is a good idea, but you must not use it too often.
Take Care Of Your Live Plants
If you have live plants in your tank, be sure to prune dead leaves that will rot and create ammonia.
Whenever you see some dead plant matter in your tank, be sure to get it out of there before it causes any problems.
So, now you know everything you need to when it comes it nitrites.
They are bad and can lead to the death of your fish, so it is always something you should be on the lookout for.
If your fish show any signs that are mentioned in this post, you need to carry out a water test to check the nitrite levels.
If the levels are above 0 ppm, you need to find out what the problem is and resolve it as soon as you possibly can, before the worst happens.